The families of flowering plants
Habit and leaf form. Trees, or shrubs, or lianas (with stilt- or aerial roots, and often myrmecophilous); laticiferous (rarely, the laticifer system restricted to the bark), or non-laticiferous. Self supporting, or epiphytic, or climbing. Leaves alternate; simple, or compound (or almost so). Lamina deeply dissected to entire; when dissected, pinnatifid, or palmatifid; pinnately veined, or palmately veined; cross-venulate. Leaves stipulate; becoming compound from primordial lobes.
Leaf anatomy. Stomata present; anisocytic (Poikilospermum). Adaxial hypodermis commonly present. Cystoliths present (e.g. Poikilospermum), or absent (?). The mesophyll containing crystals. The crystals often druses.
Axial (stem, wood) anatomy. Nodes bilacunar, or penta-lacunar (?). Secondary thickening developing from a conventional cambial ring. Primary medullary rays mixed wide and narrow.
The vessel end-walls simple. The vessels without vestured pits. The parenchyma paratracheal.
Reproductive type, pollination. Fertile flowers functionally male and functionally female. Plants monoecious. Pollination anemophilous, or entomophilous.
Inflorescence, floral, fruit and seed morphology. Flowers small; regular; 2–4 merous; cyclic. Free hypanthium absent.
Perianth sepaline; 2–4; 1 whorled. Calyx 2–4; 1 whorled; polysepalous, or gamosepalous.
Androecium 2–4. Androecial members free of the perianth; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 2–4; isomerous with the perianth; erect in bud (the filaments straight). Anthers dehiscing via longitudinal slits; tetrasporangiate. Pollen grains aperturate; 2 aperturate; porate.
Gynoecium ostensibly 1 carpelled. Carpels reduced in number relative to the perianth. The pistil 1 celled. Gynoecium monomerous (ostensibly), or syncarpous (supposedly pseudomonomerous); of one carpel (ostensibly), or eu-syncarpous (if presumed to be pseudomonomerous); superior. Carpel stylate; apically stigmatic; 1 ovuled. Placentation of the single carpel, if so interpreted, basal (or almost so). Ovary 1 locular. Gynoecium stylate. Styles 1; apical. Stigmas 1. Placentation basal. Ovules in the single cavity 1; ascending; more or less orthotropous; bitegmic; crassinucellate.
Fruit fleshy to non-fleshy. The fruiting carpel indehiscent; nucular, or drupaceous. Fruit if viewed as syncarpous, indehiscent; a drupe, or a nut. Gynoecia of adjoining flowers commonly combining to form a multiple fruit (cf. Moraceae). Embryo well differentiated. Cotyledons 2. Embryo straight.
Physiology, phytochemistry. Saponins/sapogenins absent. Proanthocyanidins present; cyanidin. Flavonols absent. Ellagic acid absent (Cecropia).
Geography, cytology. Neotropical. Sub-tropical to tropical. Tropical America. X = 7.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgrens Superorder Malviflorae; Urticales. Cronquists Subclass Hamamelidae; Urticales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; fabid; Order Rosales (as a synonym of Urticaceae).
Species 275. Genera 6; Cecropia, Coussapoa, Myrianthus, Musanga, Poikilospermum, Pourouma.
General remarks. Dubiously differing from Urticaceae (q.v.) in nodal anatomy, the stamens erect rather than inflexed in bud, and the usually multiple fruits. See Berg 1978.
Illustrations. • Pourouma cecropiaefolia: Fl. Brasil. 4 (1852–63). • Coussapoa nitida: Fl. Brasil. 4 (1852–63). • Cecropia scabra: Fl. Brasil. 4 (1852–63).
The descriptions are offered for casual browsing only. We strongly advise against extracting comparative information from them. This is much more easily achieved using the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG).
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 22nd August 2016. delta-intkey.com’.